1478 - Impact of Short versus Long Treatment Durations for Respiratory Tract Infections Caused by Non-fermenting Gram-negative Bacilli in Lung Transplant Recipients

Background: In lung transplant recipients, respiratory tract infections are associated with faster progression through stages of bronchiolitis obliterans syndrome and mortality. Common causative pathogens for respiratory tract infections (RTIs) include non-fermenting gram-negative bacilli (NFGNB). Data to guide optimal treatment durations for NFGNB RTIs in this population are limited.

Methods: This was a single-center, retrospective, cohort study of adult lung transplant recipients who received systemic antibiotic treatment for RTIs caused by NFNGB and had at least 28 days of post-treatment follow-up. Analyses were conducted for each patient’s initial NFGNB RTI as well as all independent NFGNB RTIs episodes. Groups were divided into NFGNB RTIs treated for a short (≤ 10 days) versus long ( > 10 days) duration of effective antibiotic therapy. The primary outcome was the incidence of recurrent NFGNB RTIs within 28 days post-treatment. Recurrence was defined as isolation of the same organism in a respiratory culture requiring treatment with systemic antibiotics as determined by the prescribing physician.

Results: We included 207 lung transplant recipients with 334 NFGNB RTIs (n=129 short; n=205 long) from a period of January 1, 2010 to July 1, 2019. The most common causative pathogen was P. aeruginosa (77% and 82%) and most NFGNB RTIs were treated inpatient (60% and 53%) in both groups. The median duration of therapy was 10 days and 14 days for the short and long treatment durations, respectively. The primary outcome occurred in 14/129 (11%) of the NFGNB RTIs treated for ≤ 10 days and 28/205 (14%) of those treated for > 10 days. No difference in recurrence within 28 days was detected in NFGNB RTIs treated for ≤ 10 days (aOR, 0.69; 95% CI, 0.34-1.4; p=0.149). Use of adjunctive inhaled antibiotics was associated with reduced recurrence (aOR, 0.38; 95% CI, 0.16-0.92; p=0.032).

Conclusion: In lung transplant recipients with NFGNB RTIs, no difference in infection recurrence was detected between treatment durations for ≤ 10 days compared to > 10 days. Further investigation analyzing treatment durations for respiratory tract infections as well as the utility of adjunctive inhaled antibiotics are warranted in this patient population.